Objective: The aim of this investigation was to make a comparative assessment in opening torque of implant-abutment screw joint between different implant systems by using repeated static and dynamic load.
Methods: Implants and straight abutments for cement-retained restoration were chosen from 5 manufacturers to represent a range of interface connection and abutment screw attachment. Implant/abutment assemblies selected for this study were the followings: Replace with "tri channel" internal connection (Steri-Oss), Branemark Standard abutment with external hex (Nobel Biocare), two Hungarian implant systems with tube in tube design (Dentimplant Ltd, Szentes), and ribs design (Uniplant, Budapest) and a German system with tube in tube and ribs design (Camlog, Altatec)
Full crown castings were inserted on abutments and fixture parts were polymerised in acrylic resin. We tightened abutment screws according to manufacturer's instruction. Application of torque was electronically controlled. In the cyclic test two dynamic force transducers are connected to the exciters and transmit the load to the occlusal surface. The torque necessary to loosen each screw was then recorded.
Results: Proportion of opening ad tightening torques was between 0.7-0.57 for Replace ad Branemark systems while for other implant joint these values could be calculated between 0.9-0.84.
Conclusion: From these results can be concluded that there was significant difference in decrease of torques among abutment screws which varied moderately in length and in diameter. Supported by OTKA T035024